The Gull River is a river in Algonquin Highlands and Dysart et al, Haliburton County and the single-tier municipality of Kawartha Lakes in south-central Ontario, Canada. It is in the Trent River and Lake Ontario drainage basins, and flows from southern Algonquin Provincial Park to Balsam Lake on the Trent–Severn Waterway.
The river's lowest and southernmost lake, Silver Lake, lies upon the boundary line between the granite Canadian Shield, and the Limestone sheaths which lie south of it. The lakes and rivers north of Silver Lake twist and wind between the mountains and valleys created by the retreating glaciers at the end of the ice age. The result is the spectacular and pristine wilderness that has earned Highway 35, that passes through the drainage basin, a reputation as one of the most scenic highways of Ontario.